U.S. patent application number 14/368856 was filed with the patent office on 2014-12-04 for dynamic damper device and lock-up device for fluid type power transmission device.
This patent application is currently assigned to EXEDY Corporation. The applicant listed for this patent is EXEDY Corporation. Invention is credited to Naoki Tomiyama.
Application Number | 20140353105 14/368856 |
Document ID | / |
Family ID | 48947559 |
Filed Date | 2014-12-04 |
United States Patent
Application |
20140353105 |
Kind Code |
A1 |
Tomiyama; Naoki |
December 4, 2014 |
DYNAMIC DAMPER DEVICE AND LOCK-UP DEVICE FOR FLUID TYPE POWER
TRANSMISSION DEVICE
Abstract
A dynamic damper disposed between a piston of a lock-up device
and a turbine hub of a fluid type power transmission device
includes a pair of plates into which a torque is inputted and that
is allowed to be coupled to the turbine hub, a hub flange, an
inertia member fixed to the hub flange, a torsion spring, and a
hysteresis torque generating mechanism. The hub flange is disposed
between the pair of plates while being rotatable relative to the
pair of plates. The torsion spring elastically couples the pair of
plates and the hub flange. The hysteresis torque generating
mechanism is disposed on an inner peripheral side of the hub flange
while being disposed between the pair of plates, and is configured
to generate a variable hysteresis torque between both plates and
the hub flange.
Inventors: |
Tomiyama; Naoki;
(Neyagawa-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
EXEDY Corporation |
Neyagawa-shi, Osaka |
|
JP |
|
|
Assignee: |
EXEDY Corporation
Neyagawa-shi, Osaka
JP
|
Family ID: |
48947559 |
Appl. No.: |
14/368856 |
Filed: |
February 7, 2013 |
PCT Filed: |
February 7, 2013 |
PCT NO: |
PCT/JP2013/052804 |
371 Date: |
June 26, 2014 |
Current U.S.
Class: |
192/3.23 |
Current CPC
Class: |
F16H 2045/0205 20130101;
F16H 2045/0226 20130101; F16H 2045/0278 20130101; F16H 2045/0221
20130101; F16F 15/134 20130101; F16H 45/02 20130101; F16D 3/12
20130101 |
Class at
Publication: |
192/3.23 |
International
Class: |
F16D 21/00 20060101
F16D021/00; F16D 3/12 20060101 F16D003/12 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 7, 2012 |
JP |
2012-023614 |
Claims
1. A dynamic damper device disposed between a piston of a lock-up
device and a turbine hub of a fluid type power transmission device,
comprising: a pair of plates into which a torque is inputted from
the piston, the pair of plates being configured to be coupled to
the turbine hub; an annular hub flange disposed between the pair of
plates while being rotatable relative to the pair of plates; an
inertia member fixed to the hub flange; an elastic member
elastically coupling the pair of plates and the hub flange in a
rotational direction; and a hysteresis torque generating mechanism
disposed on an inner peripheral side of the hub flange while being
disposed between the pair of plates in an axial direction, the
hysteresis torque generating mechanism being configured to generate
a variable hysteresis torque between the pair of plates and the hub
flange, wherein the hysteresis torque generating mechanism is
configured to generate a first hysteresis torque in a low
rotational speed range and generate a second hysteresis torque
greater than the first hysteresis torque in middle to high
rotational speed ranges.
2. (canceled)
3. The dynamic damper device recited in claim 1, wherein the
hysteresis torque generating mechanism includes a plurality of
sliders configured to be rotated together with the pair of plates
and be movable in a radial direction, and the plurality of sliders
are configured to be moved radially outward by means of a
centrifugal force so as to be contacted to an inner peripheral
surface of the hub flange when the pair of plates is rotated at a
predetermined rotational speed or greater.
4. The dynamic damper device recited in claim 3, wherein the
hysteresis torque generating mechanism further includes a pressing
mechanism configured to press the plurality of sliders onto at
least one of the pair of plates, the hysteresis torque generating
mechanism being configured to press each of the sliders onto the
inner peripheral surface of the hub flange by an action using a
lever principle where the part of each slider pressed onto one of
the pair of plates by the pressing mechanism serves as a
fulcrum.
5. The dynamic damper device recited in claim 4, wherein the
pressing mechanism includes a contact part being formed on at least
one of the pair of plates, the contact part being spaced from a
rotation-directional lateral surface of each of the sliders by a
clearance; and a support part supporting each of the sliders to
make each of the sliders pivotable with respect to the turbine in
the rotational direction.
6. A lock-up device for a fluid type power transmission device, the
lock-up device being configured to mechanically transmit a power
from a front cover to a turbine hub of the fluid type power
transmission device, the lock-up device comprising: a piston being
configured to be pressed onto the front cover; the dynamic damper
device recited in claim 1; and an elastic member elastically
coupling the piston and the dynamic damper device in the rotational
direction.
7. A lock-up device for a fluid type power transmission device, the
lock-up device being configured to mechanically transmit a power
from a front cover to a turbine hub of the fluid type power
transmission device, the lock-up device comprising: a piston being
configured to be pressed onto the front cover; the dynamic damper
device recited in claim 5; and an elastic member elastically
coupling the piston and the dynamic damper device in the rotational
direction.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a U.S. National stage application of
International Application No. PCT/JP2013/052804, filed Feb. 7,
2013, which claims priority to Japanese Patent Application No.
2012-023614, filed in Japan on Feb. 7, 2012, the entire contents of
which are hereby incorporated by reference.
BACKGROUND
[0002] 1. Field of Invention
[0003] The present invention relates to a dynamic damper device,
particularly to a dynamic damper device disposed between a piston
of a lock-up device and a turbine hub of a fluid type power
transmission device. Further, the present invention relates to a
lock-up device, particularly to a lock-up device for mechanically
transmitting power from a front cover to a turbine hub of a fluid
type power transmission device.
[0004] 2. Background Information
[0005] A torque converter as a fluid type power transmission device
is embedded with a lock-up device to reduce fuel consumption. The
lock-up device is disposed in a space produced between a turbine
and a front cover, and is configured to mechanically couple the
turbine and the front cover to directly transmit a torque
therebetween.
[0006] In general, the lock-up device includes a piston and a
damper mechanism. The piston is pressed onto the front cover by the
action of hydraulic pressure, and a torque is transmitted to the
piston from the front cover. The damper mechanism includes an
output-side member coupled to the turbine, and a plurality of
torsion springs for elastically coupling the piston and the
output-side member. Moreover, the torque transmitted to the piston
is transmitted to the output-side member through the plurality of
torsion springs, and is further transmitted to the turbine.
[0007] Japanese Laid-open Patent Application Publication No.
JP-A-2009-293671 describes a lock-up device in which an inertia
member is mounted to the output-side member to inhibit variation in
engine rotation. In the lock-up device described in Japanese
Laid-open Patent Application Publication No. JP-A-2009-293671, the
inertia member is mounted to the output member fixed to the turbine
while being rotatable relative thereto. Further, torsion springs
are disposed as elastic members between the output member and the
inertia member.
[0008] In the lock-up device of Japanese Laid-open Patent
Application Publication No. JP-A-2009-293671, the inertia member is
coupled to the output member through the torsion springs.
Therefore, the inertia member and the torsion springs function as a
dynamic damper, and these components attenuate variation in
rotational speed of the output-side member (turbine).
SUMMARY
[0009] Recent passenger vehicles have been demanded to suppress as
low as possible a rotational speed at which the front cover and the
turbine are coupled (hereinafter referred to as "a lock-up
rotational speed") to enhance fuel consumption. However, in
general, the engine rotational speed widely varies in a lower
engine rotational speed range. Therefore, when the lock-up
rotational speed is set to be low, the output-side rotational speed
inevitably varies more widely. In view of this, with use of such
lock-up device having the inertia member as described in Japanese
Laid-open Patent Application No. JP-A-2009-293671, variation in
rotation can be inhibited even when the lock-up rotational speed is
set to be, for instance, roughly 1200 rpm.
[0010] However, a drawback is produced that the rotational speed
widely varies at around 1600 rpm where the lock-up device having
the inertia member is designed to have a specification of
minimizing variation in output-side rotational speed at around 1200
rpm. The characteristic of variation in rotational speed, i.e., at
around what rotational speed variation in rotational speed is
minimized and maximized, is mainly attributed to the magnitude of a
hysteresis torque to be produced between the output member and the
inertia member.
[0011] The lock-up device described in Japanese Laid-open Patent
Application No. JP-A-2009-293671 is embedded with a hysteresis
torque generating mechanism, but variation in output-side
rotational speed cannot be inhibited in a wide rotational speed
range.
[0012] It is an object of the present invention to inhibit
variation in output-side rotational speed in a wide rotational
speed range even when the lock-up rotational speed is set to be
low, and further, to implement such function without enlarging the
device.
[0013] A dynamic damper device according to an aspect of the
present invention is a device disposed between a piston of a
lock-up device and a turbine hub of a fluid type power transmission
device, and includes a pair of plates, an annular hub flange, an
inertia member, an elastic member and a hysteresis torque
generating mechanism. The pair of plates is a pair of members into
which a torque is inputted from the piston and is allowed to be
coupled to the turbine hub. The annular hub flange is disposed
between the pair of plates while being rotatable relative to the
pair of plates. The inertia member is fixed to the hub flange. The
elastic member elastically couples the pair of plates and the hub
flange in a rotational direction. The hysteresis torque generating
mechanism is disposed on an inner peripheral side of the hub
flange, while being disposed between the pair of plates in an axial
direction, and is configured to generate a variable hysteresis
torque between the pair of plates and the hub flange.
[0014] In the present device, a torque is inputted into the pair of
plates through the piston, and is outputted to the turbine hub to
which the pair of plates is coupled. The hub flange, to which the
inertia member is fixed, is disposed between the pair of plates
through the elastic member. Variation in rotational speed is
inhibited by the inertia member.
[0015] The pair of plates and the hub flange are rotated relative
to each other, and a hysteresis torque generated by the hysteresis
torque generating mechanism acts between the both members. A
characteristic of variation in output-side rotational speed varies
depending on the magnitude of a hysteresis torque.
[0016] In view of the above, according to the present invention, a
hysteresis torque is configured to vary depending on rotational
speed ranges, and variation in output-side rotational speed is
configured to be reduced in a wide rotational speed range.
Therefore, even when the lock-up rotational speed is set to be low,
variation in rotational speed can be inhibited in a wide rotational
speed range.
[0017] Further, the hysteresis torque generating mechanism is
disposed on the inner peripheral side of the hub flange, while
being disposed axially between the pair of plates. Therefore, it is
possible to prevent a situation that the axial size of the device
is inevitably increased due to the hysteresis torque generating
mechanism provided therein. Yet further, the hysteresis torque
generating mechanism can be composed of a small number of
components. Thus, cost reduction can be implemented.
[0018] Preferably, the hysteresis torque generating mechanism is
configured to generate a first hysteresis torque in a low
rotational speed range and generate a second hysteresis torque
greater than the first hysteresis torque in middle to high
rotational speed ranges.
[0019] When a small hysteresis torque is generated between the pair
of plates and the hub flange, variation in output-side rotational
speed is reduced in the low rotational speed range. Contrarily to
this, when a large hysteresis torque is generated therebetween,
variation in output-side rotational speed is reduced in the middle
rotational speed range. In view of the above, according to the
present invention, the first hysteresis torque is configured to be
generated in the low rotational speed range, whereas the greater
second hysteresis torque is configured to be generated in the
middle to high rotational speed ranges. Therefore, variation in
engine-side rotational speed can be inhibited in a wide rotational
speed range.
[0020] Preferably, the hysteresis torque generating mechanism
includes a plurality of sliders configured to be rotated together
with the pair of plates and be movable in a radial direction, and
the plurality of sliders are configured to be moved radially
outward by means of a centrifugal force to be contacted to an inner
peripheral surface of the hub flange when the pair of plates is
rotated at a predetermined rotational speed or greater.
[0021] A hysteresis torque, configured to vary depending on the
rotational speed, can be generated by utilizing the centrifugal
force acting on the sliders. Therefore, the hysteresis torque
generating mechanism can be implemented with a simple
structure.
[0022] Preferably, the hysteresis torque generating mechanism
further includes a pressing mechanism configured to press the
plurality of sliders onto at least either of the pair of plates,
and is configured to strongly press each of the sliders onto the
inner peripheral surface of the hub flange by an action using a
principle of lever where the part of each slider pressed onto
either of the pair of plates by the pressing mechanism serves as a
fulcrum.
[0023] To generate a large hysteresis torque, the sliders are
required to be enlarged for increasing the centrifugal force
thereof. However, a large occupied space is required for the
purpose. By contrast, when the sliders are reduced for the purpose
of compactness, the centrifugal force acting on the reduced sliders
is also reduced. Thus, a large hysteresis torque cannot be
generated.
[0024] In view of the above, according to the present invention,
the pressing mechanism for pressing the sliders onto at least
either of the plates is further provided, and it is configured that
a large hysteresis torque can be generated even with small sliders
by utilizing the principle of lever.
[0025] Preferably, the pressing mechanism includes a contact part
and a support part. The contact part is formed on at least either
of the pair of plates, and is disposed away from a
rotation-directional lateral surface of each of the sliders through
a clearance. The support part supports each of the sliders to make
each of the sliders pivotable with respect to the turbine in the
rotational direction.
[0026] In the present device, when being contacted to the hub
flange by means of the centrifugal force, the sliders attempt to
rotate together with the hub flange. Thus, each slider pivots about
the support part. With the pivot of each slider, a lateral surface
of each slider is contacted to the contact part of the relevant
plate.
[0027] Here, the sliders can be strongly pressed onto at least
either of the pair of plates with a simple structure, and a large
hysteresis torque can be easily generated.
[0028] A lock-up device for a fluid type power transmission device
according to another aspect of the present invention is a device
configured to mechanically transmit a power from a front cover to a
turbine hub of the fluid type power transmission device, and
includes: a piston configured to be pressed onto the front cover;
the dynamic damper device recited in any of the aforementioned
inventions; and an elastic member elastically coupling the piston
and the dynamic damper device in the rotational direction.
[0029] According to the present invention as described above, in a
lock-up device, the lock-up rotational speed can be set to be as
low as possible, and in addition, variation in turbine rotation can
be inhibited in a wide rotational speed range. Therefore, low fuel
consumption can be achieved. Further, a mechanism for generating a
variable hysteresis torque can be implemented with a simple
structure without increasing the axial size of the device.
BRIEF DESCRIPTION OF THE DRAWINGS
[0030] FIG. 1 is a cross-sectional structural view of a torque
converter equipped with a lock-up device according to an exemplary
embodiment of the present invention.
[0031] FIG. 2 is a cross-sectional structural view of the lock-up
device.
[0032] FIG. 3 is a cross-sectional view of a first plate.
[0033] FIG. 4 is a partial view of FIG. 3 seen in an arrow IV
direction.
[0034] FIG. 5 is an enlarged view of a convex part of the first
plate.
[0035] FIG. 6 is a cross-sectional view of a second plate taken
along a line VI-VI in FIG. 8.
[0036] FIG. 7 is another cross-sectional view of the second plate
taken along a line VII-VII in FIG. 8.
[0037] FIG. 8 is a view of FIG. 6 seen in a direction VIII.
[0038] FIG. 9 is a view of FIG. 7 seen in a direction IX.
[0039] FIG. 10 is a cross-sectional view of a hub flange and an
inertia member.
[0040] FIG. 11 is a partial view of FIG. 10 seen in a direction
XI.
[0041] FIG. 12 is a schematic view of a hysteresis torque
generating mechanism.
[0042] FIG. 13 is a partial cross-sectional view of the hysteresis
torque generating mechanism.
[0043] FIG. 14 is a characteristic diagram of engine rotational
speed and variation in rotational speed.
[0044] FIG. 15 is an actuation principle diagram for explaining an
action of the hysteresis torque generating mechanism.
[0045] FIG. 16 is a diagram corresponding to FIG. 12 and
illustrates another exemplary embodiment of the hysteresis torque
generating mechanism.
[0046] FIG. 17 is a diagram corresponding to FIG. 12 and
illustrates yet another exemplary embodiment of the hysteresis
torque generating mechanism.
DESCRIPTION OF THE EXEMPLARY EMBODIMENTS
[0047] Entire Structure
[0048] FIG. 1 illustrates a torque converter as a fluid type power
transmission device according to an exemplary embodiment of the
present invention. In FIG. 1, an engine is disposed on the left
side, whereas a transmission is disposed on the right side. A line
O-O depicted in FIG. 1 is a rotary axis line of the torque
converter. It should be noted that a main body of the torque
converter is illustrated while a part thereof is not
illustrated.
[0049] A torque converter 1 is a device for transmitting power from
a crankshaft of the engine to an input shaft of the transmission.
The torque converter 1 mainly includes a front cover 2 into which
power is inputted, an impeller 3, a turbine 4, a stator 5 and a
lock-up device 6.
[0050] The outer peripheral part of the front cover 2 and that of
the impeller 3 are fixed to each other by bolts 7. The front cover
2 and the impeller 3 form a fluid chamber. The turbine 4 is
disposed in opposition to the impeller 3 within the fluid chamber.
The turbine 4 includes a turbine shell 8, a plurality of turbine
blades 9 fixed to the inside of the turbine shell 8, and a turbine
hub 10 fixed to the inner peripheral part of the turbine shell 8.
The turbine hub 10 has a tubular part 10a extending in the axial
direction, and a disc-shaped flange 10b extending radially outward
from the tubular part 10a. Further, the inner peripheral part of
the turbine shell 8 is fixed to the outer peripheral part of the
flange 10b by rivets 13. It should be noted that a spline hole 10c
is formed in the inner peripheral part of the turbine hub 10.
Further, the input shaft of the transmission (not illustrated in
the drawings) is coupled to the spline hole 10c. On the other hand,
the stator 5 is a mechanism for regulating the flow of operating
oil from the turbine 4 to the impeller 3. The stator 5 is disposed
between the impeller 3 and the turbine 4.
[0051] Lock-Up Device 6
[0052] FIG. 2 illustrates the lock-up device 6 taken out from the
torque converter 1. The lock-up device 6 is a device for
mechanically coupling the front cover 2 and the turbine 4 when the
engine rotational speed reaches a predetermined rotational speed
(the lock-up rotational speed). As illus1trated in FIG. 1, the
lock-up device 6 is disposed between the front cover 2 and the
turbine 4. The lock-up device 6 includes a piston 15, a dynamic
damper device 16 and a plurality of first torsion springs 17.
[0053] Piston 15
[0054] The piston 15 has a tubular part 15a on the inner peripheral
part thereof, and the tubular part 15a is formed by bending the
inner peripheral part toward the engine. Further, the tubular part
15a is supported by the outer peripheral surface of the tubular
part 10a of the turbine hub 10 while being slidable in the axial
direction and the rotational direction. Yet further, an annular
friction member 18, configured to be pressed onto the lateral
surface of the front cover 2, is fixed to an outer peripheral part
15b of the piston 15.
[0055] Dynamic Damper Device 16
[0056] The dynamic damper device 16 includes a pair of a first
plate 21 and a second plate 22, a hub flange 23, an inertia member
24, a plurality of second torsion springs 25, and a hysteresis
torque generating mechanism 26.
[0057] First and Second Plates 21 and 22
[0058] FIG. 3 illustrates a cross-sectional view of the first plate
21, whereas FIG. 4 illustrates a part of FIG. 3 seen in a direction
IV
[0059] As illustrated in these drawings, the first plate 21 is a
disc-shaped member and has a circular aperture 21 bored in the
center part thereof, and four engaging protrusions 21b formed on
the outer peripheral part thereof. The four engaging protrusions
21b are formed to protrude to the outer peripheral side and slant
toward the engine. The plural first torsion springs 17 are disposed
among these engaging protrusions 21b. The circumferential end
surfaces of the four engaging protrusions 21b can be engaged with
the circumferential end parts of the first torsion springs 17.
[0060] Further, the first plate 21 has six stop pin apertures 21c
formed on the inner peripheral side of the engaging protrusions
21b, and six accommodation parts 21d formed on the further inner
peripheral side of the stop pin apertures 21c to accommodate the
second torsion springs 25. Three circular-arc openings 21e are
bored and located on the inner peripheral side of the accommodation
parts 21d. Each of the three openings 21e has engaging recesses 21f
that are formed on the both ends thereof to dent to the inner
peripheral side. Further, three spring-holding openings 21g are
bored among the three openings 21e in the circumferential
direction.
[0061] Circular convex parts 21h are formed on the outer peripheral
side of the three openings 21e and the three spring-holding
openings 21g to protrude toward the second plate 22. As illustrated
in an enlarged view of FIG. 5, each convex part 21h is formed by
extruding a part of the first plate 21 toward the second plate 22.
The tip end of each convex part 21h is made in the form of a flat
surface, and protrudes from the surrounding surface thereof toward
the second plate 22 by a predetermined distance. The tip end
surface is contacted to the lateral surface of the hub flange
23.
[0062] Rivet apertures 21i are respectively bored and located on
the inner peripheral side of the three openings 21e.
[0063] FIGS. 6 and 7 illustrate cross-sectional views of the second
plate 22, whereas FIG. 8 illustrates a front view of the second
plate 22. FIG. 9 illustrates a part of FIG. 7 seen in a direction
IX and a cross-sectional view of the part taken along a line IX-IX.
FIG. 6 is a cross-sectional view of FIG. 8 taken along a line
VI-VI, whereas FIG. 7 is a cross-sectional view of FIG. 8 taken
along a line VII-VII.
[0064] As illustrated in these drawings, the second plate 22 is a
disc-shaped member and has a circular aperture 22a bored in the
center part thereof, six stop pin apertures 22c bored in the outer
peripheral part thereof, and six accommodation parts 22d formed on
the further inner peripheral side of the stop pin apertures 22c to
accommodate the second torsion springs 25. Three circular-arc
openings 22e are bored and located on the inner peripheral side of
the accommodation parts 22d. Each of the three openings 22e has
engaging recesses 22f that are formed on the both ends thereof to
dent to the inner peripheral side. Further, three spring-holding
openings 22g are bored among the three openings 22e in the
circumferential direction.
[0065] Circular convex parts 22h are formed on the outer peripheral
side of the three openings 22e and the three spring-holding
openings 22g to protrude toward the first plate 21. Each convex
part 22h is formed similarly to each convex part 21h formed on the
first plate 21.
[0066] Rivet apertures 22i are respectively bored and located on
the inner peripheral side of the three openings 22e.
[0067] Further, the second plate 22 has slider support portions 28
formed in three positions on the inner peripheral side of the
accommodation parts 22d. The slider support portions 28 compose a
part of the hysteresis torque generating mechanism 26, and support
sliders (to be described) in a radially movable state. As
illustrated in FIGS. 7 and 9, the respective slider support
portions 28 are formed among the three openings 22e. When described
in detail, the inner peripheral parts of the three openings 22e are
formed as offset parts 22j that are extruded toward the first plate
21 while being convexly curved to the inner peripheral side in a
circular-arc shape. Further, the slider support portions 28 are
formed among the three offset parts 22j in the circumferential
direction. As illustrated in FIG. 9, each slider support portion 28
is formed about the spring-holding opening 22g in the
circumferential direction of both sides and with a width W1.
Further, the circumferential ends thereof serve as contact parts
28a configured to collide with each slider to be described.
[0068] As illustrated in FIGS. 1 and 2, the first plate 21 and the
second plate 22, structured as described above, are fixed to each
other by rivets 30 penetrating through the rivet apertures 21i and
22i of the respective plates 21 and 22, while the inner peripheral
part of the first plate 21 and offset parts 22j of the second plate
22 are contacted to each other. Further, the outer peripheral parts
of the both plates 21 and 22 are fixed by stop pins 31 penetrating
through the stop pin apertures 21c and 22c of the respective plates
21 and 22, while being axially separated at a predetermined
clearance. Both plates 21 and 22, except for the parts thereof
fixed to each other by the rivets 30, are disposed in opposition to
each other through the predetermined clearance set by the stop pins
31.
[0069] As illustrated in FIGS. 1 and 2, a driven plate 33 is fixed
to the flange 10b of the turbine hub 10 by the rivets 13. This
driven plate 33 is formed in an annular shape, and has a plurality
of pawls 33a that are formed on the outer peripheral end thereof to
bend and extend toward the engine. Further, the plural pawls 33a
are engaged with the engaging recesses 21f of the first plate 21
and the engaging recesses 22f of the second plate 22. Therefore,
the first and second plates 21 and 22 are rotated in
synchronization with the turbine hub 10.
[0070] Further, the second torsion springs 25 are accommodated
within the accommodation parts 21d and 22d of the both plates 21
and 22.
[0071] Hub Flange 23 and Inertia Member 24
[0072] As illustrated in FIG. 10 and FIG. 11, which is a view of
FIG. 10 seen in a direction XI, the hub flange 23 is a disc-shaped
member having an aperture 23a in the center part thereof. The
annular inertia member 24 is fixed to the outer peripheral end of
the hub flange 23 by rivets 34. Further, six circular-arc elongated
apertures 23c are bored and located on the inner peripheral side of
a part, on which the inertia member 24 is mounted, of the hub
flange 23, and six accommodation parts 23d are formed on the
further inner peripheral side of the elongated apertures 23c. The
trunk parts of the stop pins 31 penetrate through the elongated
apertures 23c. Thus, the hub flange 23 is rotatable relatively to
the first and second plates 21 and 22 within an angular range in
which each elongated aperture 23c is formed. Further, the
respective accommodation parts 23d are formed in the same positions
as the accommodation parts 21d and 22d of the both plates 21 and
22. The second torsion springs 25 are accommodated in the
accommodation parts 23d.
[0073] As described above, the convex parts 21h and 22h are formed
on the first and second plates 21 and 22, and are contacted to the
both lateral surfaces of the hub flange 23. Therefore, a clearance
corresponding to the height of the respective convex parts 21h is
produced between one lateral surface of the hub flange 23 and the
first plate 21 except for the positions on which the convex parts
21h are formed, whereas a clearance corresponding to the height of
the respective convex parts 22h is produced between the other
lateral surface of the hub flange 23 and the second plate 22 except
for the positions in which the convex parts 22h are formed.
[0074] Hysteresis Torque Generating Mechanism 26
[0075] The hysteresis torque generating mechanism 26 is disposed
between the first plate 21 and the second plate 22 in the axial
direction, while being disposed on the inner peripheral side of the
hub flange 23 in the radial direction. The hysteresis torque
generating mechanism 26 is configured to generate a variable
hysteresis torque between the first and second plates 21 and 22 and
the hub flange 23.
[0076] FIG. 12 schematically illustrates a basic structure of the
hysteresis torque generating mechanism 26. It should be noted that
FIG. 12 is a schematic diagram, and therefore, some of the
respective members illustrated in FIG. 12 may have dimensions,
shapes and so forth different from those of their relevant members
illustrated in the other drawings.
[0077] The hysteresis torque generating mechanism 26 includes the
slider support portions 28 formed in the aforementioned second
plate 22, three sliders 36 respectively disposed in the slider
support portions 28 while being radially movable, and springs 37
respectively disposed correspondingly to the sliders 36.
[0078] Each slider 36 is disposed between the two contact parts 28a
formed on both ends of each slider support portion 28. The outer
peripheral part of each slider 36 is formed in a circular-arc
shape, and is contactable to the inner peripheral surface (the
surface of the aperture 23a, hereinafter referred to as "an inner
peripheral end surface") of the hub flange 23. The inner peripheral
part of each slider 36 is formed in a shape along the outer
peripheral surface of the turbine hub 10, and has a support
protrusion 36a that is formed on the circumferential middle part
thereof to protrude to the inner peripheral side. Further, an
opening 36b for accommodating each spring 37 is formed on the outer
peripheral side of each support protrusion 36a, while being located
in a position corresponding to its relevant pair of the
spring-holding openings 21g and 22g of the first and second plates
21 and 22.
[0079] A plurality of circular-arc support recesses 10d are formed
on the outer peripheral surface of the turbine hub 10. Further, the
plural support recesses 10d support the support protrusions 36a of
the sliders 36. Here, as illustrated in FIGS. 9 and 12, the width
between the contact parts 28a formed on both ends of each slider
support portion 28 is W1, whereas the width of each slider 36 is
W2, which is less than W1. Clearances are produced between both
lateral surfaces of each slider 36 and the contact parts 28a
opposed thereto. Thus, each slider 36 is radially movable, while
being pivotable about the support protrusion 36a in a range of the
clearance.
[0080] The support protrusions 36a of the sliders 36 and the
contact parts 28a of the slider support portions 28, as described
above, compose a pressing mechanism for pressing the sliders 36
onto a part of the second plate 22 (i.e., the contact parts
28a).
[0081] As illustrated in FIG. 13, each spring 37 is accommodated in
the opening 36b of each slider 36, while being held by its relevant
pair of the spring-holding openings 21g and 22g of the first and
second plates 21 and 22. One end of each spring 37a, disposed on
the radially inside, is contacted to the inner peripheral end
surface of the opening 36b of each slider 36, whereas the other end
of each spring 37, disposed on the radially outside, is contacted
to the outer peripheral end surfaces of the relevant pair of the
spring-holding openings 21g and 22g of the first and second plates
21 and 22. While the lock-up device 6 is not being rotated (i.e., a
centrifugal force is not acting on the device), each slider 36 is
urged radially inward by each spring 37 without being contacted to
the inner peripheral end surface of the hub flange 23.
[0082] First Torsion Springs 17
[0083] As illustrated in FIGS. 1 and 2, the plural first torsion
springs 17 are members for elastically coupling a drive plate 40
and the first plate 21, which are fixed to the piston 15, in the
rotational direction. An intermediate member 42 is disposed for
covering the outer peripheral parts and the transmission-side
lateral parts of the plural first torsion springs 17. The plural
first torsion springs 17 are restricted from axially and radially
moving by the piston 15 and the intermediate member 42.
[0084] Further, the intermediate member 42 is rotatable relative to
the drive plate 40 and the first plate 21. Yet further, the
intermediate member 42 is a member for causing each pair (i.e., two
torsion springs) of the plural first torsion springs 17 to act in
series.
[0085] Action
[0086] First, an action of the torque converter main body will be
briefly explained.
[0087] During rotation of the front cover 2 and the impeller 3, the
operating oil flows from the impeller 3 to the turbine 4, and power
is transmitted from the impeller 3 to the turbine 4 through the
operating oil. The power transmitted to the turbine 4 is
transmitted to the input shaft (not illustrated in the drawings) of
the transmission through the turbine hub 10.
[0088] When the rotational speed of the input shaft reaches a
predetermined rotational speed, the lock-up device 6 is turned on,
and power is mechanically transmitted from the front cover 2 to the
2 5 turbine hub 10 through the lock-up device 6. Specifically, the
piston 15 is moved toward the engine by means of variation in
hydraulic pressure, and the friction member 18 of the piston 15 is
pressed onto the front cover 2. As a result, the piston 15 is
unitarily rotated with the front cover 2, and power is transmitted
from the front cover 2 to the turbine hub 10 through the piston 15,
the first torsion springs 17 and the dynamic damper device 16.
[0089] Action of Dynamic Damper Device
[0090] In the dynamic damper device 16, the power inputted into the
first and second plates 21 and 22 is transmitted to the turbine hub
10 through the driven plate 33. The hub flange 23 and the inertia
member 24 are herein mounted to the first and second plates 21 and
22 through the second torsion springs 25. Therefore, variation in
rotation of the engine can be effectively inhibited. In this
regard, detailed explanation will be hereinafter made.
[0091] As represented in FIG. 14, in general, when the rotational
speed of an engine is reduced, variation in rotation of the engine
to be caused by variation in combustion is increased (a
characteristic E1). At this time, where the inertia member 24
(i.e., the dynamic damper device 16) is not provided, variation in
speed of rotation to be outputted from a torque converter is
gradually increased when the engine rotational speed is reduced. By
contrast, where the dynamic damper device 16 is provided as with
the present exemplary embodiment, it is possible to reduce
variation in rotational speed of a turbine as an output-side
component at around a specific engine rotational speed (around 1200
rpm in the example of FIG. 14) (characteristics E2 and E3).
[0092] A difference between the characteristics E2 and E3 in a low
rotational speed range is attributed to the magnitude of a
hysteresis torque in the hysteresis torque generating mechanism 26.
The characteristic E2 relates to a case that a hysteresis torque is
relatively large, whereas the characteristic E3 relates to a case
that a hysteresis torque is relatively small. In the characteristic
E2, variation in rotational speed of the turbine is reduced when
the engine is rotated at around a rotational speed less than 1200
rpm, is then maximized at around 1500 rpm, and is gradually reduced
in a rotational speed range greater than around 1500 rpm. In the
characteristic E3, variation in rotational speed of the turbine
indicates the minimum value less than that of the characteristic E2
around when the engine rotational speed exceeds 1200 rpm, and then,
exceeds the characteristic E2 and indicates the maximum value when
the engine rotational speed is around 1600 rpm.
[0093] As is obvious from these characteristics, variation in
rotational speed of the turbine is smaller in a low engine
rotational speed range when a hysteresis torque is smaller, whereas
variation in rotational speed of the turbine is smaller in a middle
engine rotational speed range when a hysteresis torque is larger.
Variation in rotational speed of the turbine is less affected by
the magnitude of a hysteresis torque in a high engine rotational
speed range.
[0094] In view of the above, the hysteresis torque generating
mechanism 26 according to the present exemplary embodiment is
configured to change a hysteresis torque depending on rotational
speed ranges. Specifically, a hysteresis torque to be generated by
the hysteresis torque generating mechanism 26 becomes small in a
low engine rotational speed range and becomes large in middle and
high engine rotational speed ranges.
[0095] Action of Hysteresis Torque Generating Mechanism
[0096] Using FIG. 15, explanation will be made for an action that a
hysteresis torque varies depending on the rotational speed
ranges.
[0097] First, in the low rotational speed range, a centrifugal
force f1 acting on each slider 36 is relatively small. Therefore,
as illustrated in FIG. 15(a), each slider 36 is urged radially
inward by means of an urging force f2 of its relevant spring 37,
while the outer peripheral surface of each slider 36 is not
contacted to the inner peripheral end surface of the hub flange 23.
Therefore, a hysteresis torque is relatively small. Only a
hysteresis torque exists that is attributed to friction among
respective components.
[0098] When the rotational speed is increased, the centrifugal
force f1 acting on each slider 36 is increased. When such large
centrifugal force f1 acts on each slider 36, each slider 36 is
moved to the outer peripheral side against the urging force f2 of
its relevant spring 37. Thus, as illustrated in FIG. 15(b), the
outer peripheral surface of each slider 36 and the inner peripheral
surface of the hub flange 23 are contacted to each other at around
a point a. Therefore, at this time, a hysteresis torque greater
than that in the low rotational speed range is generated.
[0099] Further, while variation in rotational speed is caused, the
turbine hub 10 and the hub flange 23 are rotated in reverse phases.
Therefore, each slider 36, contacted to the inner peripheral end
surface of the hub flange 23, receives a force B, and accordingly,
attempts to rotate in the clockwise direction in FIG. 15. Under
such condition, as illustrated in FIG. 15(c), the support
protrusion 36a of each slider 36 is contacted to the turbine hub 10
at a point c, and receives a force f4 from the contact point c. As
described above, clearances are herein produced between the both
lateral surfaces of each slider 36 and the contact parts 28a of
each slider support portion 28. Accordingly, each slider 36 is
supposed to further receive a clockwise moment. As a result, one
lateral surface of each slider 36 is supposed to be strongly
pressed onto its relevant contact part 28a, and serves as a
fulcrum. Further, in the drawing, a position in the vicinity of the
left side of each slider 36 serves as a load. Thus, each slider 36
is further strongly pressed onto the inner peripheral surface of
the hub flange 23 by the principle of lever.
[0100] As described above, a hysteresis torque, which is greater
than that to be generated in the conditions illustrated in FIGS.
15(a) and 15(b), is generated between components rotated relative
to each other, i.e., between the hub flange 23 and a component
group including the first and second plates 21 and 22 and the
turbine hub 10.
[0101] With the aforementioned structure, as represented in FIG.
14, the characteristic of variation in rotational speed of the
turbine becomes the characteristic E3 in the low rotational speed
range, and becomes the characteristic E2 in the middle to high
rotational speed ranges. Therefore, variation in rotational speed
of the turbine can be suppressed low in the entire engine
rotational speed ranges.
[0102] Features
[0103] A small hysteresis torque is generated in the low rotational
speed range, whereas a large hysteresis torque is generated in the
middle to high rotational speed ranges. Therefore, variation in
rotational speed of the turbine can be inhibited in a wide
rotational speed range.
[0104] The hysteresis torque generating mechanism 26 is disposed
between the first plate 21 and the second plate 22. Therefore, the
device can be formed with a compact size in the axial
direction.
[0105] A hysteresis torque is caused to vary using the centrifugal
force acting on the sliders 36. Therefore, with a simple structure,
different hysteresis torques can be generated depending on the
rotational speed ranges.
[0106] Each slider 36 is caused to pivot about the support
protrusion 36a to be contacted onto the contact part 28a of the
second plate 22, and thereby, the contact position serves as a
fulcrum. Thus, each slider 36 is configured to be further strongly
pressed onto the inner peripheral surface of the hub flange 23 by
the principle of lever. Therefore, a large hysteresis torque can be
generated with a simple structure.
Other Exemplary Embodiments
[0107] The present invention is not limited to the exemplary
embodiment as described above, and a variety of changes or
modifications can be made without departing from the scope of the
present invention.
[0108] The structure of the hysteresis torque generating mechanism
is not limited to that described in the aforementioned exemplary
embodiment. Any structure can be applied as long as a hysteresis
torque to be generated varies depending on rotational speed
ranges.
[0109] The aforementioned exemplary embodiment has been explained
by exemplifying the torque converter as a fluid type power
transmission device. However, a fluid coupling without a stator may
be applied as a fluid type power transmission device.
[0110] FIGS. 16 and 17 illustrate other exemplary embodiments of a
pressing mechanism for generating a large hysteresis torque by
causing sliders to pivot.
[0111] In the exemplary embodiment illustrated in FIG. 16, each of
sliders 36' has a support recess 36a' instead of the support
protrusion 36a provided in the aforementioned exemplary embodiment.
The support recess 36a' has a surface convexly curved to the outer
peripheral side in a circular-arc shape. A turbine hub 10' has
support protrusions 10d', each of which is fitted into each support
recess 36a'. The tip end surface of each support protrusion 10d' is
formed in a circular-arc shape along the circular-arc surface of
each support recess 36a'.
[0112] Further, in the exemplary embodiment illustrated in FIG. 17,
each of sliders 36'' has a support recess 36'' basically structured
similarly to the corresponding element illustrated in FIG. 16. A
turbine hub 10'' has support recesses 10d'' respectively recessed
to the inner peripheral side in a circular-arc shape. Further, each
of rollers 50 is fitted into each pair of these support recesses
36a'' and 10d''.
[0113] The aforementioned exemplary embodiments illustrated in
FIGS. 16 and 17 can also achieve advantageous effects similar to
those achieved by the aforementioned exemplary embodiment.
[0114] With employment of a dynamic damper device of the present
invention, a lock-up device is enabled to set the lock-up
rotational speed as low as possible, and in addition, to inhibit
variation in turbine rotation in a wide rotational speed range.
Thus, low fuel consumption can be implemented. Further, it is
possible to implement a mechanism for generating a variable
hysteresis torque with a simple structure without increasing the
axial size of the lock-up device.
* * * * *